Metallized paper and process for making same



Dec- 8, 1964 L. J. NovAK Eri-Al. 3,160,550

METALLIZED PAPER AND PROCESS FOR MAKNG SAME 2 Sheetsf-Sheet 1 Filed Feb. 29. 1960 Fig. 7 I8 INVENTORS LEO d, NOI/AK WILBUR M. BOLTON ATTORNEY S Dec. 8, 1964 1 .1. NovAK ETAL METALLIZED PAPER AND PROCESS FOR MAKING SAME Filed Feb, 29. 1960 2 Sheet-Sheec 2 INVENTORS LEO J. NOV/4K W/LBUR M O-TON BY Mm ATTORNELQ United States Patent O 3,160,559 A nnsratrrann paran AND rnoenss non Marina; sama Leo .71'. Noyal/r, Cedar Rapids, iowa, and Wilbur M. Bolton, Piqua, Ghia, assignors to Union Carbide Corporation, New York, NSY.

Filed Ech. Z9, 196th Ser. No. 11,508 3 Ciairns. (Si. lol- 184) This invention relates to nietahized paper and the like which has a wide variety of uses, for example as dielectric material, wrapping paper, and decorative paper sheet and webbing.

It has been proposed heretofore to produce a dielectric such as used for making condensers by applying an electrical insulating coating on one side of a sheet of material such as paper, and then applying thereover one or more coatings of varnish or lacquer. Diiculties have been encountered, however, in providing a coating of uniform thickness and a dielectric which is devoid of weak spots interfering with the operation of a condenser made therefrom.

The present invention provides a met-allized paper sheet having a continuous ilm of metal laid thereon which is of uniform thickness and high purity of metal.

It is an object of the invention to produce rnetallized sheet material of the character described which is useful for various purposes and wherein one or more layers of metal are provided of controlled thickness and uniformity which are electrically insulated from each other.

Another object is to provide a decorative sheet composed of a backing of paper of cellulose or regenerated cellulose, e.g., cellophane, which comprises configurations or ligures thereon formed by metal deposited from the gaseous phase as by thermal decomposition of a gaseous metal compound.

Another object of the invention is to provide a metallized continuous sheet which comprises a metal foil made by gas plating rand which is united to a backing sheet of paper or the like.

Another object of the invention is to provide `a exible metallized wrapping paper sheet which is formed by gas plating one or both Vsides of -a sheet of paper and whereby the paper is made substantially water and oil proof.

Still another object of the invention is to provide a metallized sheet or substrate which substrate consists of paper impregnated with heat resistant Vmaterial such as silicone and which impregnated paper has been subjected to gas plating to give it a iiexible coating or film of metal, the metal being applied to one or more sides of the substrate or on selected surface areas.

These and other objects and advantages will occur to those skilled in the art from the following description.

The invention is illustrated by the accompanying drawings wherein- FIGURE l illustrates in perspective a roll of paper sheet made in accordance with this invention and which consists of paper metallized on one side by the deposition of a thin layer of metal by gas plating;

FIGURE 2 is a cross-sectional View taken substantially on the line 2-2 of FIGURE l, and looking in the direction of the arrows;

FiGURE 3 illustrates in section a modified lrnetallized papr in which both sides of the paper sheet vare metaluze FIGURE 4 illustrates in section another modication similar to FIGURE 3, wherein the paper or substrate metallized by gas plating comprises an impregnated paper sheet having an outer surface film of metal;

FIGURE 5 illustrates in section -a metallized sheet as used for la condenser and comprising built-up layers of i@ Patented Dec. 8, 1964 ICC paper, varnish coatings and metal united to form an integnal sheet of dielectric material;

FIGURE 6 illustrates in perspective a metallized roll, such as useful as wrapping paper, or decorative sheet, wallpaper or the like, formed by gas plating paper sheet or webbing to deposit congurations or the like on selected areas als shown; Y

FIGURE 7 depicts diagrammatically a method of metallizing paper as drawn from :a roll by combining the ysame with a sheet of Imetal ifoil such -as produced by gas plating; `and FIGURE 8 illustrates in section an apparatus for con tinuous gas plating of paper sheet `as drawn from a takeoii roll.

Referring in more detail to the drawings, particularly to FIGURES l, Zand 3, there is provided a roll of paper sheet 10 composed of paper 11, having a layer or lilrn l2 of metal, the iatter being gas plated onto the paper sheet to provide ra continuous metal lm or layer of substantially uniform thickness. Where desired, the paper sheet is gas plated on both sides to provide the same with a thin coating lof metal on opposite sides of the sheet or web as illustrated in FIGURE 3, :the paper sheet 13 carrying the metal film 14.

In the modication illustrated in FIGURE 4, the substrate consists of paper impregnated with high melting resin such as silicone resins, e.g., hydrolyzed silicon esters containing about V% silicon doxide. For reinforcing the Vpaper the pulp may contain from l0 to 50% of inorganic fibers such as glass fibers, metal coated glass bers, asbestos fibers and the like. A metallized substrate of this character is illustrated in FIGURE 4, wherein the resin impregnated paper pulp 16 comprises reinforcing iibers 17 as aforementioned. The substrate is gas plated on opposite sides to provide the same with a thin continuous metal coating or film of metal as at 1S.

in the preparation of condensers, a ilexible laminated dielectric sheet is built up as illustrated in FIGURE 5, and wherein the sarne comprises a composite or laminated sheet composed of layers of paper 20, metal Z1 gw pirated thereon, and a varnish or lacquer coating 22. The metal coating in each instance is applied by gas plating to provide a flexible anduniformly coated paper sheet. Metal coatings as gas plated thereon have a thickness of 0.001 to 0.01 inch and provide a uniform and continuous layer of metal. The uniformity of the metal coating or lrn, and lack of porosity, distinguish such gas plated metal coatings over other metal coatings.

Utilizing gas plating technique for deposition of the metal provides a dielectric material having improved resistivity to rupture or breakdown in use than conventional metallized dielectric material. These improved results may be accounted for due to the nature of the metal deposit which is denser and more uniform than in the case of condensed vaporized metal and electroplated metal deposits. Gas plated metal as deposited from thermally decomposed metal bearing compounds the metal deposits in molecular layers as pure, nascent metal. Such gas plating metal deposits are uniform over the surface of the substrate surface and are free from porous and occluded impurities.

Decorative paper having a design or conliguration deposited thereon by gas plating may be provided, as illustrated in FIGURE 6. Such a decorative paper roll is alsdann rolls 35 rotated as illustrated by the arrows, to produce an integral or composite metallized sheet 36. lf desired, a coating adhesive layer may be applied to the paper sheet 32 prior to pressure rolling the gas plated metal foil thereon. A suitable apparatus and method of making Vmetal foil by gas plating is illustrated and described inV the U.S. patent to Davis et al. 2,685,121.

In FIGURE 8 is a schematic illustration of an apparatus for gas plating paper sheet as drawn continuously from a roll, the gas plating apparatus being shown in section. The preferred arrangement comprises a preheating compartment. 4l) which is directly connected with a gas plating chamber 41, which, in turn, is provided with a post-cooling compartment 4Z. Paper sheet which is to be gas plated to provide a metallized sheet is drawn from a take-ofi roll 44 as at 4S, and passed through the preheating and gas plating chamber 41. After plating the metallized sheet 46 is drawn through the cooling compartment 42 and rolled up on a storage roll 47. A motor 48 is suitably arranged to drivethe roll 47 through a V-belt 49, yas shown on the drawing.

Heating of the compartment et) is effected by means of the electrical resistance coils 50 which extend longi-V tudinally of the compartment at opposite sides of the paper sheet. The gaseous metal compound, eg., metal carbonyl is introduced into the plating chamber 41 through an inlet pipe 52 and exhaust waste gases are discharged therefrom through an outlet pipe 53. For indicating the temperature and pressure in the gas plating chamber suitable indicating instruments are provided, as shown at S4 and 55. Cooling gas, such as carbo-.n dioxide is passed through the cooling compartment 42, the cooling gas being admitted through pipe 57 and discharging through line 58. Y

The through-put rate of paper sheet for plating depends upon the facility `and speed at which the paper can be heated prior to entrance ofthe same into the gas plating chamber. For high input rates longer preheating compartments or chambers must be provided to assure that the paper is heated to the proper temperature before passing into the gas plating chamber.

The deposition of metal lm or layer .by gas plating with heat-decomposable gaseous metal compounds produces a thin, flexible film which is distinctly diiferent from ordinary wet electroplating and metal spray application methods. By gas plating metal deposits are formed having exceptionally high metal purity since the decomposition and deposition of the metal is carried out in situ and without contamination. The gas plating deposition thus functions as a purification step. A metal having a purity of 50 parts per million cubic feet, or less, in the gaseous state is provided which upon decomposition and deposition, under non-contaminating conditions, may produce a metal deposited hlm having a purity of to 10 parts per hundred billion weight.

It is believed, although not as yet confirmed by actual tests, that this ultra high purity property of the metal lms as deposited by gas plating, that is employing a heat decomposable gaseous metal compound and decomposing the compound in the presence of the heated substrate,

and which substrate is maintained in a controlled atmosp that the presence of even relatively minute amounts of impurities, especially inorganics, have a profound effect upon the ultimate physical characteristics of metal coatings or layers.

ln carrying out the gaseous metal plating it is, of course, necessary that the material or substrate be heated to at least a minimum temperature of decomposition required for the metal bearing gas employed. It is also preferable that the plating gas flow counter-current to the moving heated substrate, the temperature of the substrate will be lowered slightly by Contact with the heat decomposable gaseous metal compound during its decomposition and deposit of metal thereon.

While itis preferred to use metal carbonyls as the plating gaseous compound, various other metal bearing gases such as copper acetylacetonate, metal hydrides, metal nitrides, and metal organic compounds which are heat decomposable at a relatively low temperature may be used. In particular, nickel carbonyl may be used,

as well as other meals which form volatile decomposable carbonyls and which are suitable for vapor phase deposition. Such other compounds as may be employed las a carbonyl are iron, molybdenum, chromium, cobalt,

tunvsten, ruthenium, and other various metals. rlfhese metal carbonyls are Volatilized and thermally decomposed at temperatures which leave the material or substrate which is to be plated with metal unaffected by the temperatures employed. Mixtures of two or more metal carbonyls or gaseous metal bearing compounds can be used to deposit their respective metallic constituents in situ. In the use of gaseous metal compounds, particularly the carbonyls, it is preferred to add a small amount of a catalyst thereto, such as silicon or titanium chloride. Y

The gaseous metal compound, including` the catalyst, are introduced into the plating system as vapors with an inert carrier gas, such as a nonoxidizing medium as nitrogen, hydrogen, helium, argon or the like. To the tlow of carrier gas there may be added the required amount of catalyst for example, to nickel carbonyl the addition of from 0.1 to 10.0 vols. (percent) of the silicon or titanium chloride is introduced. YThe particular amount of catalyst may be varied to suit the metal compound being used and the conditionsemployed for effecting the gas plating. Y

The process of the invention provides a metallized exible paper or decorative substrate which, as hereto- Vfore mentioned, may be used as a decorative Wrapping paper, condenser coil dielectric and other uses where such a metallized flexible paper or cellulose sheet is useful. The metallic coating laid thereon by gas plating is of a thin, uniform thickness which can be readily controlled by limiting the time and amount of gaseous metal compound brought into contact with the substrate. The conductivity is controllable by Varying the thickness of the coating since the uniformity of plate is exceptionally accurate. Thus, for example, a paper sheet may be produced having a coating of nickel thereon which shows an electrical resistance of 1/2 to l0 ohms per inch. In this connection, it has been unexpectedly found that such a thin paper sheet can be treated under conditions so as to gas plate the same with metal at a rapidity such that the paper or substrate does not have sufficient time to become heated to a temperature such as to cause it c to deteriorate. The gas plating may be carried out to deposit the metal in a matter of a second and thus by repeating the operation the desired thickness of gas plated metal may be deposited on the substrate.Y

There are given below a number of examples of plating gas and concentrations used, with temperatures and omitting the introduction of catalysts, which may be added to the carrier gas, as described above. The particular concentrations and conditions which may be suitably employed are set forth in the following examples but it will be noted by varying the length of time or plating chamber, and speed of the movement of the substrate through the plating chamber, that suitable operating conditions for particular application may be readily predetermined and the invention is accordingly not limited to the specic conditions set forth in the examples.

Example I Using nickel carbonyl as plating gas, the conditions of operation were as follows:

Temperature of heater over which paper substrate passes 700 F. Carrier gas Cort-0.5% vol. NH3. Flow rate of nickel carbonyl, cc./min. 30 cc. per min. Time of plating 5 seconds. Pressure in the system Substantially atmospheric.

Winding speed, ft./min. 24 ft. per min.

A flexible metallized paper sheet is provided having a lustrous metal coating of nickel. Electrical resistance tests indicated the metallized sheet to have l5 ohms resistance per square inch on each side. The addition of ammonia gas in the CO2 carrier gas may be omitted where a high luster is not desired.

Example Il Using nickel acetylacetonate the conditions of operation may be as follows:

Temperature of heater over which paper substrate passes 800 F. Carrier gas (carbon dioxide). Flow rate of nickel acetylacetonate 40 cc. per min. Time of plating seconds. Pressure in the system Atmospheric. Winding speed, ft. /min 50 ft. per min.

Example III Using copper acetylacetonate the conditions of operation may be as follows:

Temperature of heater over which paper substrate passes 900-950 F. Carrier gas (helium). l Flow rate of copper -acetylacetonate 30 cc. per min.

Time of plating 8 seconds. Pressure in the system Substantially atmospheric. `Winding speed 60 ft. per min. Example 1V Gas plating of paper sheet is carried out as described in Example I using chromium carbonyl as the heat-decomposable gaseous metal compound whereby chromium metal is deposited onto the surface of the paper sheet.

Example V Paper sheet is plated with molybdenum metal by carrying out the process similarly as described in Example I and employing molybdenum carbonyl as the gas plating metal bearing compound.

Example VI Tungsten is plated onto paper sheet by utilizing tungsten carbonyl as the metal bearing heat-decomposable gaseous compound and carrying out the gas plating as described in Example I.

Example VII The gas plating time may be varied depending upon the thickness of the plating deposit desired. An important advantage of gas plating over other deposition methods lies in the phenomenal speed at which the metal deposit can be deposited. For example, very thin uniform plating deposit of metal can be deposited as a continuous layer on the substrate in 0.01 of a second. This is a very important factor commercially since use can be made of high speed gas plating equipment. Where a microfilm plating of metal is desired,t his can be effected by exposure to heat-decomposable metal bearing compounds at' decomposing temperatures for 3/100 to $47 of a second. Various metal bearing compounds may be used for gas plating. Organo-metallics employed for gas plating permit plating in micro-seconds, the gas plating is accomplished at extremely fast rates, the limiting factor being the time required to heat the paper or substrate being gas plated.

It is to be noted that the conditions set forth in the above examples may be varied substantially fon the diierent operating conditions and for the particular apparatus employed. For example, if the material to be plated is a substrate of relatively low melting or deteriorating point, then the same will be plated at lower temperatures and using the correspondingly low temperature decomposing gaseous metal compound. Similarly, Where the conditions require non-oxidizing during plating, the plating chamber will be continuously purged With the non-oxidizing gas such as nitrogen, helium, argon or the like.

ln the continuous gas plating paper substrate, as described, it is preferable that the metal plated paper come out of the plating apparatus at a temperature low enough to prevent oxidation of the metal deposited surface. This is accomplished by immediately passing the hot metallized paper into an atmosphere of cooling inert gas to cool the metallized paper sheet to approximately room temperature (70 F.) before moving vit out of the cooling chamber and onto storage rolls.

Where desired, the paper sheet, after gas plating to provide the paper with a thin iiexible coating of metal such as nickel, chromium, molybdenum or the like, the thus metallized sheet is coated with a thin coating of resin. This provides a metallized paper having improved physical properties, such as adhesion, flexibility, permanence of luster, Washability and durability. Suitable useful resin coating compositions may comprise synthetic resins dissolved in solvent, eg., epoxy resin plastics, silicone resins and the like. Other coatings, such as nitrocellulose lacquers, vegetable oil modified alkyd resins and the like resinous coatings which are iiexible and durable may be utilized.

In addition to the uses aforementioned for gas plated paper of this invention, the same may be employed in fabricating semi-conductors, static resistors, as Well as condensers and other electrical equipment where semiconductors and insulated metal iilms are required.

While in the foregoing specification there has been described and illustrated a particular embodiment of the invention and specific examples have been given of didierent plating gases, it will be understood that the invention is also applicable to the metallizing of various types of thin, iiexible sheets made of different substrate. It will also be understood that the examples given are merely illustrative of the gaseous plating conditions and which may be Widely varied depending upon the gaseous metal compound being used and the substrate being plated. Such modifications Which come within the scope of the appended claims are intended to be protected thereby.

What is claimed is:

1. A method of producing a laminated metallized paper adapted for use as a dielectric sheet material which comprises the steps of applying on one side of said paper sheet an insulating coating of an epoxy resin, applying on the opposite side of said paper sheet a metal coating of substantially pure metal by decomposing a heat decomposable gaseous metal compound on said paper sheet surface, applying an epoxy resinous coating over said metal coating, and applying a second similarly metallized paper sheet onto said last-mentioned resinous coating with the paper surface thereof directly contacting the resinous coating, to provide a laminated muiti-rnetallized paper sheet structure.

2. A method of preparing a flexible composite laminated metallized paper sheet material useful as a dielectric sheet material in electrical condensers, said method consisting of providing a plurality of paper sheets, gas plating a uniform continuous layer of metal having a uniform thickness and of approximately 15 ohms resistance per square inch onto one of the major surfaces of each of said sheets, securing the metal surface of one of said sheets to the paper surface of the other of said sheets by an epoxy resinous coating to provide a laminated sheet and applying over the uncoated side of one of said paper sheets a thin coating film of a lacquer resinous coating to provide a composite laminated dielectric sheet.

3. An article of manufacture composed of a flexible laminated metallized dielectric sheet material comprising two paper sheets each coated on one side only with a lm of substantially pure metal, the metal surface ofV one of said sheets being secured to the paper surface of the other of each sheets by atlm of epoxy resin, and the paper surface of said secured together sheet materialrbeing covered by a lm of epoxy resin.

References Cited by the Examiner UNITED STATES PATENTS 1,376,737 5/21 Tscheike. 2,362,884 11/44 Clark 117-71 2,367,152 1/45 Strab 117-71 2,382,432 8/ 45 McManus et al. 2,439,137 4/48 .Keller 156-151 2,615,007 10/52 Greenlee 117-161 2,748,031 5/56 Kag 117-212 X 2,754,230 7/56 McLean etal. 117-107 2,785,383 3/57 Foster 117-161 2,886,468 5/59 Hoover 117-107 2,923,651 2/60 Petriello 154-46 OTHER REFERENCES Fiberglass Products forPapermaking, Ovvens-Corning, February 1954; 15 pages spec. 4 relied on.

EARL M. BERGERT, Primary Examiner.

25 RICHARD D. NEVIUS., Examiner. 

3. AN ARTICLE OF MANUFACTURE COMPOSED OF A FLEXIBLE LAMINATED METALLIZED DIELECTRIC SHEET MATERIAL COMPRISING TWO PAPER SHEETS EACH COATED ON ONE SIDE ONLY WITH A FILM OF SUBSTANTIALLY PURE METAL, THE METAL SURFACE OF ONE OF SAID SHEETS BEING SECURED TO THE PAPER SURFACE OF THE OTHER OF EACH SHEETS BY A FILM OF EPOXY RESIN, AND THE PAPER SURFACE OF SAID SECURED TOGETHER SHEET MATERIAL BEING COVERED BY A FILM OF EPOXY RESIN. 